Project Abstract Opioid overdose continues to be a public health problem of unprecedented scale in the United States. Our team is currently conducting randomized pragmatic trials of novel naloxone distributions approaches in two large health systems -- Kaiser Permanente Colorado and Denver Health. The parent grant (R01DA042059) for this diversity supplement has been designed to reduce opioid overdose risk behavior and overdose among patients prescribed chronic opioid therapy. The primary outcome is patient-reported risk behavior, measured by a survey instrument which includes several established scales. However, it is not known how well these survey measures of risk behavior predict risk behavior measures derived from the electronic health record (EHR), such as overdose, substance use treatment admissions, and urine toxicology results. In addition to the survey and EHR data, we have identified a need to consider social and environmental factors that may contribute to opioid risk behavior and overdose. In our parent trial, such social and environmental data could be available for all patients based on address. However, the predictive properties of these data on individual level opioid risk behavior have not been evaluated. Exploring the use of these data with this supplement will enhance the parent trial and represent an innovative training opportunity for a postdoctoral trainee. The scientific goals of this supplement are to: (1) augment the parent intervention trial database of EHR and survey data with global environmental data on social determinants of health (e.g., income, education, drug arrests at the county or census tract level); (2) determine the predictive validity of risk behavior survey measures by examining associations between survey responses and measures of risk behavior derived from the EHR; and (3) identify predictors of opioid risk behavior in trial eligible patients in the two large health care systems that are study sites of parent grant. We will employ data linkage and hierarchical statistical models to accomplish these aims. This supplement also has three career development goals for Dr. Anh Nguyen, a promising postdoctoral trainee with a background in Sociology: (1) to acquire expertise on the determinants of opioid risk behavior; (2) advance his knowledge and skills in epidemiologic study design, health systems interventions, EHR analytics and hierarchical modeling; and (3) to learn to present at local and national meetings, lead (first-author) peer-reviewed manuscripts, and write a grant proposal. Our research group includes mentors who possess the substantive knowledge and technical expertise essential to achieve Dr. Nguyen?s career development goals, including Drs. Ingrid Binswanger, Jason Glanz and Stan Xu.